Message-ID: <CO6PR11MB563553020E9A0275390E3763EEF42@CO6PR11MB5635.namprd11.prod.outlook.com>
Date: Thu, 23 May 2024 16:45:29 +0000
From: "Wang, Weilin" <weilin.wang@...el.com>
To: Ian Rogers <irogers@...gle.com>
CC: Namhyung Kim <namhyung@...nel.org>, Arnaldo Carvalho de Melo
	<acme@...nel.org>, Peter Zijlstra <peterz@...radead.org>, Ingo Molnar
	<mingo@...hat.com>, Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Jiri Olsa <jolsa@...nel.org>, "Hunter, Adrian" <adrian.hunter@...el.com>, Kan
 Liang <kan.liang@...ux.intel.com>, "linux-perf-users@...r.kernel.org"
	<linux-perf-users@...r.kernel.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "Taylor, Perry" <perry.taylor@...el.com>,
	"Alt, Samantha" <samantha.alt@...el.com>, "Biggers, Caleb"
	<caleb.biggers@...el.com>
Subject: RE: [RFC PATCH v9 0/7] TPEBS counting mode support



> -----Original Message-----
> From: Ian Rogers <irogers@...gle.com>
> Sent: Wednesday, May 22, 2024 9:04 PM
> To: Wang, Weilin <weilin.wang@...el.com>
> Cc: Namhyung Kim <namhyung@...nel.org>; Arnaldo Carvalho de Melo
> <acme@...nel.org>; Peter Zijlstra <peterz@...radead.org>; Ingo Molnar
> <mingo@...hat.com>; Alexander Shishkin
> <alexander.shishkin@...ux.intel.com>; Jiri Olsa <jolsa@...nel.org>; Hunter,
> Adrian <adrian.hunter@...el.com>; Kan Liang <kan.liang@...ux.intel.com>;
> linux-perf-users@...r.kernel.org; linux-kernel@...r.kernel.org; Taylor, Perry
> <perry.taylor@...el.com>; Alt, Samantha <samantha.alt@...el.com>; Biggers,
> Caleb <caleb.biggers@...el.com>
> Subject: Re: [RFC PATCH v9 0/7] TPEBS counting mode support
> 
> On Tue, May 21, 2024 at 10:39 AM <weilin.wang@...el.com> wrote:
> >
> > From: Weilin Wang <weilin.wang@...el.com>
> >
> > Changes in v9:
> > - Update the retire_latency result print and metric calculation method. Plugin
> > the value to evsel so that no special code is required.
> > - Update --control:fifo to use pipe instead of named pipe.
> > - Add test for TPEBS counting mode.
> > - Update Document with more details.
> >
> > Changes in v8:
> > - In this revision, the code is updated to base on Ian's patch on R modifier
> > parser https://lore.kernel.org/lkml/20240428053616.1125891-3-
> irogers@...gle.com/
> 
> I pulled the first patch of these 3, to clean up the tool events into
> its own patch and hopefully addressed Namhyung's feedback:
> https://lore.kernel.org/lkml/20240503232849.17752-1-
> irogers@...gle.com/
> It is looking for review.
> 
> I think in general it'd be useful when posting the series to include
> the patches it is dependent on, that way we can also make changes to
> those patches (for example the missed perf-list documentation of the
> 'R' modifier).

Hi Ian,

I will include the 2nd patch from the series in the TPEBS patch set next time. 

Thanks,
Weilin
> 
> Thanks,
> Ian
> 
> 
> 
> > After this change, there is no special code required for R modifier in
> > metricgroup.c and metricgroup.h files.
> >
> > Caveat of this change:
> >   Ideally, we will need to add special handling to skip counting events with R
> > modifier in evsel. Currently, this is not implemented so the event with :R will
> > be both counted and sampled. Usually, in a metric formula that uses
> retire_latency,
> > it would already require to count the event. As a result, we will endup count
> the
> > same event twice. This should be able to be handled properly when we
> finalize our
> > design on evsel R modifier support.
> >
> > - Move TPEBS specific code out from main perf stat code to separate files in
> > util/intel-tpebs.c and util/intel-tpebs.h. [Namhyung]
> > - Use --control:fifo to ack perf stat from forked perf record instead of
> sleep(2) [Namhyung]
> > - Add introductions about TPEBS and R modifier in Documents. [Namhyung]
> >
> >
> > Changes in v7:
> > - Update code and comments for better code quality [Namhyung]
> > - Add a separate commit for perf data [Namhyung]
> > - Update retire latency print function to improve alignment [Namhyung]
> >
> > Changes in v6:
> > - Update code and add comments for better code quality [Namhyung]
> > - Remove the added fd var and directly pass the opened fd to data.file.fd
> [Namhyung]
> > - Add kill() to stop perf record when perf stat exists early [Namhyung]
> > - Add command opt check to ensure only start perf record when -a/-C given
> [Namhyung]
> > - Squash commits [Namhyung]
> >
> > Changes in v5:
> > - Update code and add comments for better code quality [Ian]
> >
> > Changes in v4:
> > - Remove uncessary debug print and update code and comments for better
> > readability and quality [Namhyung]
> > - Update mtl metric json file with consistent TmaL1 and TopdownL1
> metricgroup
> >
> > Changes in v3:
> > - Remove ':' when event name has '@' [Ian]
> > - Use 'R' as the modifier instead of "retire_latency" [Ian]
> >
> > Changes in v2:
> > - Add MTL metric file
> > - Add more descriptions and example to the patch [Arnaldo]
> >
> > Here is an example of running perf stat to collect a metric that uses
> > retire_latency value of event MEM_INST_RETIRED.STLB_HIT_STORES on a
> MTL system.
> >
> > In this simple example, there is no MEM_INST_RETIRED.STLB_HIT_STORES
> sample.
> > Therefore, the MEM_INST_RETIRED.STLB_HIT_STORES:p count and
> retire_latency value
> > are all 0.
> >
> > ./perf stat -M tma_dtlb_store -a -- sleep 1
> >
> > [ perf record: Woken up 1 times to write data ]
> > [ perf record: Captured and wrote 0.000 MB - ]
> >
> >  Performance counter stats for 'system wide':
> >
> >        181,047,168      cpu_core/TOPDOWN.SLOTS/          #      0.6 %
> tma_dtlb_store
> >          3,195,608      cpu_core/topdown-retiring/
> >         40,156,649      cpu_core/topdown-mem-bound/
> >          3,550,925      cpu_core/topdown-bad-spec/
> >        117,571,818      cpu_core/topdown-fe-bound/
> >         57,118,087      cpu_core/topdown-be-bound/
> >             69,179      cpu_core/EXE_ACTIVITY.BOUND_ON_STORES/
> >              4,582      cpu_core/MEM_INST_RETIRED.STLB_HIT_STORES/
> >         30,183,104      cpu_core/CPU_CLK_UNHALTED.DISTRIBUTED/
> >         30,556,790      cpu_core/CPU_CLK_UNHALTED.THREAD/
> >            168,486      cpu_core/DTLB_STORE_MISSES.WALK_ACTIVE/
> >               0.00 MEM_INST_RETIRED.STLB_HIT_STORES:p       0        0
> >
> >        1.003105924 seconds time elapsed
> >
> > v1:
> > TPEBS is one of the features provided by the next generation of Intel PMU.
> > Please refer to Section 8.4.1 of "Intel® Architecture Instruction Set
> Extensions
> > Programming Reference" [1] for more details about this feature.
> >
> > This set of patches supports TPEBS in counting mode. The code works in the
> > following way: it forks a perf record process from perf stat when
> retire_latency
> > of one or more events are used in a metric formula. Perf stat would send a
> > SIGTERM signal to perf record before it needs the retire latency value for
> > metric calculation. Perf stat will then process sample data to extract the
> > retire latency data for metric calculations. Currently, the code uses the
> > arithmetic average of retire latency values.
> >
> > [1] https://www.intel.com/content/www/us/en/content-
> details/812218/intel-architecture-instruction-set-extensions-programming-
> reference.html?wapkw=future%20features
> >
> >
> > Weilin Wang (7):
> >   perf vendor events intel: Add MTL metric json files
> >   perf data: Allow to use given fd in data->file.fd
> >   perf stat: Fork and launch perf record when perf stat needs to get
> >     retire latency value for a metric.
> >   perf stat: Plugin retire_lat value from sampled data to evsel
> >   perf stat: Add command line option for enabling tpebs recording
> >   perf Document: Add TPEBS to Documents
> >   perf test: Add test for Intel TPEBS counting mode
> >
> >  tools/perf/Documentation/perf-list.txt        |    1 +
> >  tools/perf/Documentation/topdown.txt          |   30 +
> >  tools/perf/arch/x86/util/evlist.c             |    6 +
> >  tools/perf/builtin-stat.c                     |   24 +
> >  .../arch/x86/meteorlake/metricgroups.json     |  127 +
> >  .../arch/x86/meteorlake/mtl-metrics.json      | 2551 +++++++++++++++++
> >  .../perf/tests/shell/test_stat_intel_tpebs.sh |   27 +
> >  tools/perf/util/Build                         |    1 +
> >  tools/perf/util/data.c                        |    7 +-
> >  tools/perf/util/evsel.c                       |   53 +
> >  tools/perf/util/evsel.h                       |    5 +
> >  tools/perf/util/intel-tpebs.c                 |  301 ++
> >  tools/perf/util/intel-tpebs.h                 |   30 +
> >  tools/perf/util/stat.h                        |    1 +
> >  14 files changed, 3163 insertions(+), 1 deletion(-)
> >  create mode 100644 tools/perf/pmu-
> events/arch/x86/meteorlake/metricgroups.json
> >  create mode 100644 tools/perf/pmu-events/arch/x86/meteorlake/mtl-
> metrics.json
> >  create mode 100755 tools/perf/tests/shell/test_stat_intel_tpebs.sh
> >  create mode 100644 tools/perf/util/intel-tpebs.c
> >  create mode 100644 tools/perf/util/intel-tpebs.h
> >
> > --
> > 2.43.0
> >

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